Experimental Study of Rubberized Asphalt Emulsion Modified Portland cement concrete

The poor fatigue properties and high rigidity of cement asphalt emulsion treated mis(CETM) have for a long time been problems restricting its further development making it impossible for C-ETMto be used as surface layer materials. In this paper, a new kind of cement asphalt emulsion composite-rubberized asphalt emulsion modified Portland cement concrete (RACC) was proposed, which was formed by dispersing rubberized aSPhalt emulsion coated coarse aggregates into cement mortar matrix. In order to evaluate systematically the performance of RACC, laboratory tests with nearly one thousand SPecimen were conducted for resilient modulus, fatigue properties, ultimate ban and length,abrasion, temperature contraction, and dry shrinkage. The experimental results show that the problems existed in C-ETM have to a great extends been solved by RACc. To verify the field performance and inquire into paving technology, teSt road appearsatlsfactory it is concluded that when thed ape surface laycr of semi-rigid base course, RACC is more for surface layer material than both Portland cement concrete(PCC) and asphalt concrete(AC)

Microscopic and Dynamic Rheological Characteristics of Crumb Rubber Modified Asphalt

A test for crumb rubber modified asphalt containing 20% crumb rubber particles（30 mesh） was performed using a scanning electron microscope（SEM）.The experimental results indicate that the crumb rubber particles are evenly distributed in the asphalt.Shear rate sweep and shear-temperature sweep tests on the crumb rubber modified asphalt at-20-80 ℃ using a dynamic shear rheology（DSR） instrument,were carried out.The tests show that the complex modulus decreases with increasing temperature;at equivalent temperature,higher load frequencies lead to a larger complex modulus,and this value increasingly decreases as the temperature increases;the phase angle increases with temperature and decreases as the load frequency increases.It can be concluded that the rutting resistance limiting temperature of crumb rubber modified asphalt is 78 ℃,and the anti-fatigue limiting temperature is 16 ℃,which shows that the asphalt has preferable rutting resistance characteristics at high temperature,as well as anti-fatigue characteristics.In addition,the complex modulus master curve at different temperatures was plotted according to the time temperature equivalence principle,which allows the study of the dynamic state behavior of crumb rubber modified asphalt at a wide range of load frequency.

Creep Characteristics of Crumb Rubber Modified Asphalt Binder

Crumb rubber modified asphalt containing 20 percent crumb rubber particles of 30 mesh has been examined by Scanning Electron Microscope （SEM） to observe the microcosmic appearance and the characteristic distribution of crumb rubber particles in asphalt. The SEM pictures reveal that the crumb rubber particles distribute evenly in the asphalt and they are compatible well with asphalt. The shear creep test of crumb rubber modified asphalt was carried out at -10 ℃ and 40 ℃ by Dynamic Shear Rheology （DSR）. The shearing deformation at different temperature and creep stiffness modulus curve at loading stage of crumb rubber modified asphalt have been measured. The stiffness modulus of crumb rubber modified asphalt is much temperature sensitive and it decays much quick at the early stage of loading than normal asphalt. The rate of decay of stiffness modulus is slow at the subsequent stage and stiffness modulus approaches to a stable value at the final stage at a higher temperature. In addition, Burgers model is suitable to describe and simulate experimental results of viscoelastic properties of the crumb rubber modified asphalt.

Performance Characterization of CR/PU Asphalt for Potential Application in Assembled Fast-Repairing Engineering

Conventional repairing methods for asphalt pavement have some inconveniences,such as insufficient strength,and are typically time-consuming.To address these issues,this study proposes a new technological method to design and prepare a high-performance assembled asphalt concrete block for fast repair of the potholes.A series of composite modified asphalt binders with 10%crumb rubber(CR)and different dosages(0%,1%,3%,5%)of polyurethane(PU)are examined to determine the optimized binder.Subsequently,the corresponding asphalt mixtures are prepared for further comparison and assessment of engineering properties,such as moistureinduced damage,high-temperature deformation,and low-temperature cracking characteristics.The test results show that PU can significantly improve the high-temperature performance and hardness of(crumb rubber modified asphalt)CRMA binder;3%PU contributes allowing the resistance of CRMA mixture to moisture-induced damage at higher levels,particularly under water whole immersion;as 3%PU is added,the high-temperature rutting deformation resistance of the CRMA mixture increases significantly,and the low-temperature anti-cracking properties are also improved slightly.Therefore,the innovatively designed high-quality assembled fast-repairing asphalt concrete block is recommended as an appropriate option for highway maintenance.

Using thermodynamic parameters to study self-healing and interface properties of crumb rubber modified asphalt based on molecular dynamics simulation

The thermodynamic property of asphalt binder is changed by the addition of crumb rubber,which in turn influences the self-healing property as well as the cohesion and adhesion within the asphalt-aggregate system.This study investigated the self-healing and interface properties of crumb rubber modified asphalt(CRMA)using thermodynamic parameters based on the molecular simulation approach.The molecular models of CRMA were built with representative structures of the virgin asphalt and the crumb rubber.The aggregate was represented by SiO2 and Al2O3 crystals.The selfhealing capability was evaluated with the thermodynamic parameter wetting time,work of cohesion and diffusivity.The interface properties were evaluated by characterizing the adhesion capability,the debonding potential and the moisture susceptibility of the asphalt-aggregate interface.The self-healing capability of CRMA is found to decrease as the rubber content increases.The asphalt-Al2O3 interface with higher rubber content has stronger adhesion and moisture stability.But the influence of crumb rubber on the interfacial properties of asphalt-SiO2 interface has no statistical significance.Comparing with the interfacial properties of the asphalt-SiO2 interface,the asphalt-Al2O3 interface is found to have a stronger adhesion but a worse moisture susceptibility for its enormous thermodynamic potential for water to displace the asphalt binder.

变温条件下胶粉改性沥青混凝土抗裂特性研究

为探究胶粉改性沥青混凝土在水利工程环境下的抗裂性能,本文基于小梁弯曲试验及全应力-应变曲线脆性指标,探究了变温条件下胶粉改性沥青混凝土的抗裂性能。结果表明:胶粉改性沥青抗裂性能最优时的配比为80M,掺量20%;低温条件下,胶粉改性沥青混凝土的抗弯强度及峰值应变优于基质沥青混凝土;温度越低,沥青混凝土的脆性指标越大,试件越容易开裂;胶粉的加入降低了基质沥青混凝土的脆性指标,使其抗裂性能有所提升,同时改变了基质沥青混凝土在-10℃时的受力状态,其应力-应变曲线由脆性特征转变为塑性特征。本文研究有望为面板选材提供新思路。

轻度解交联橡胶粉干法改性SMA13性能研究

通过沥青混合料车辙试验、小梁弯曲试验、冻融劈裂及浸水马歇尔试验,研究了不同掺量轻度解交联橡胶粉(LDCR)对干法改性SMA13高温性能、低温性能与水稳定性的影响。结果表明,掺入LDCR提高了SMA13的高温性能,尤其当掺量≥2%时,混合料的动稳定度超过4.5%SBS改性SMA13(对照组);2%掺量的LDCR干法改性SMA13低温抗裂性最优;总体上LDCR干法改性SMA13的水稳定性低于对照组。综合考虑,LDCR的最佳掺量为2%,与对照组相比,可降低材料成本约5%。

废胎胶粉和天然胶乳改性沥青的老化和流变性能研究

【目的】研究废胎胶粉和天然胶乳改性沥青的耐老化和流变性能。【方法】利用天然橡胶(Natural Rubber,NR)胶乳和废胎胶粉(Crumb Rubber,CR)制备橡胶沥青,通过针入度、软化点、延度和动态剪切流变试验,对比分析基质沥青和橡胶改性沥青老化前后常规性能和流变性能。【结果】结果表明,CR和NR胶乳的加入降低了橡胶沥青的针入度等级,提高了橡胶沥青的软化点和延度。与常规沥青相比,CR掺量高达8%,NR胶乳掺量高达4%时,橡胶沥青的复数模量和抗车辙性能均得到了显著提高。【结论】CR和NR胶乳的加入可提高改性沥青的总体性能,改善沥青路面的耐久性。

废旧胶粉/SBS复合改性沥青高温抗车辙性能研究

为提升沥青结合料的高温抗车辙性能,本研究使用CR和SBS两种聚合物对基质沥青进行复合改性。首先,基于常规的沥青性能试验(针入度、软化点和延度试验),对不同掺量下的CR和SBS单一聚合物改性沥青进行高-低温性能研究;继而,利用常规性能试验研究CR掺量对废旧胶粉/SBS复合改性沥青性能的影响,其中SBS掺量固定为2%,仅改变复合改性沥青中CR的掺量;最后,基于动态流动剪切仪(Dynamic Shear Rheometer,DSR)对废旧胶粉/SBS复合改性沥青进行多应力蠕变松弛(Multiple Stress Creep and Recovery,MSCR)试验,利用不可恢复蠕变柔量(Jnr)和应变恢复率(R)两个指标进一步研究废旧胶粉/SBS复合改性沥青高温抗车辙性能。结果表明,2%SBS和12%CR复合改性沥青的抗车辙性能优异,甚至优于SBS掺量为4.5%的SBS改性沥青。

胶粉复合改性沥青的研制及工业化生产

以某公司加工的环烷基和中间基原油为原料,通过优化原油配比,采用常减压蒸馏工艺,通过控制减压蒸馏工艺条件,生产出符合技术标准要求且能够用于改性沥青的基质沥青原料。通过筛选与基质沥青配伍性好的胶粉、助剂添加比例及工艺条件优化,研制出符合技术规范要求的胶粉复合改性沥青并进行了工业试生产。对工业生产的产品检测及专业部门鉴定结果表明,胶粉复合改性沥青产品各项技术指标符合JT/T798-2019《路用废胎胶粉橡胶沥青》技术要求,成功实现了工业化生产和应用。

SBS与胶粉复合改性沥青制备及多孔混合料性能评价

为利用废胶粉(crumbrubber,CR)制备用于多孔沥青混合料(porousasphalt,PA)的高黏改性沥青,通过SBS与CR复合并添加增粘剂与稳定剂制备了高黏改性沥青,根据针入度、软化点、延度和60℃动力黏度确定了SBS与CR的最佳比例及增黏剂用量,并研究了PA-13的路用性能。结果表明:SBS与胶粉对沥青针入度和软化点具有一定改善作用,然而SBS对沥青延度改善作用有限且胶粉对其有负面影响;SBS与胶粉均能提高沥青的动力黏度,且根据性能推荐高黏改性沥青中SBS、胶粉、增粘剂的用量分别为5.5%、14%、3%;PA-13路用性能测试成果表明自制的高黏改性沥青能够为混合料提供杰出的高低温和水稳定性。此外,与高黏沥青相关文献相比,自制高黏沥青性能优良。

胶粉改性沥青在高速公路路面养护中的应用研究

以京张高速公路养护实况为例,针对胶粉改性沥青在高速公路路面养护中的应用进行探讨,介绍了胶粉改性沥青中沥青、集料、矿料级配掺配的各项指标要求,分析了最佳油石比的确定方法,对制备完成的胶粉改性沥青混合料进行高温稳定性和低温抗裂性检验,结果均满足相关规范的要求。

Effect of SBS and crumb rubber on asphalt modification:A review of the properties and practical application

Owing to the environmental protection potential and the desirable high performance capabilities,asphalt rubber(AR)and styrene-butadiene-styrene(SBS)modified asphalt have been widely used.However,the poor construction workability and segregation issues of AR,along with the exorbitant cost of SBS modified asphalt,are of the serious problems that plague their application scope.Moreover,SBS/crumb rubber(CR)modified asphalt is gradually becoming widespread and it therefore becomes incumbent to find appropriate ways to mitigate the issues that may limit its use.As a consequence,it becomes crucial to analyze the interaction between CR and SBS modifiers in the composite mixture,as well as evaluate the influence of modifier dosage on the performance of the modified asphalt.This study presents a comprehensive review of the effects of SBS modifier,CR modifier and composite SBS/CR on the performance of modified asphalts.Macro analysis and micro analysis,including analysis on the conventional physical properties,are carried out.It can uncover the interaction between modifier and asphalt,which reveals how the modifiers influence the properties of modified asphalts.This study will serve as a source of invaluable information to researchers,engineers,and designers,informing them the development,potential and challenges of the CR,SBS and SBS/CR modified asphalts,the optimum contents to attain the best performance along with the mechanism involved.

活化废胶粉改性沥青路用性能及微观机理研究

为改善废胶粉改性沥青的储存稳定性及路用性能,采用一种新型助剂——多烷基苯酚二硫化物对废胶粉进行活化处理。通过制备不同废胶粉掺量的活化废胶粉改性沥青(AMA)和所对应的未活化废胶粉改性沥青(UMA),研究沥青路用性能随活化废胶粉掺量的变化规律。同时,对活化废胶粉改性沥青的高低温性能及微观作用机理进行研究。结果表明:废胶粉经助剂活化后,表面变得蓬松多孔且溶胀裂解更加充分,使其吸收了更多的轻质组分,分布更加均匀,从而改善了废胶粉改性沥青的储存稳定性、低温性能和施工和易性,但是其高温性能有所下降。活化废胶粉改性沥青中废胶粉最佳掺量为25%~30%。

SBS/LNBR/CR复合改性沥青密封胶的制备和性能研究

沥青路面在服役过程中,由于路面结构、气候和荷载的影响易出现早期裂缝,影响路面的长期使用寿命。采用液体丁腈橡胶(LNBR)、SBS和胶粉(CR)复合改性沥青制备裂缝修补密封胶,首先用软化点、锥入度、弹性恢复、流动值、黏度等技术指标,研究了基质沥青种类、液体橡胶掺量、改性工艺、胶粉掺量对密封胶性能的影响;随后利用荧光显微镜和红外光谱试验评价改性剂在复合改性沥青中的分散性;利用离析软化点试验评价改性剂对复合改性沥青密封胶的储存稳定性的影响。结果表明,选择90#基质沥青、3%液体丁腈橡胶、4%SBS时,随着胶粉掺量的增加,密封胶的软化点、弹性恢复和黏度均提高,流动值变好,但锥入度和储存稳定性稍有降低,当胶粉掺量20%时密封胶的综合性能最佳。

多种类沥青及复合改性材料常规-流变性能相关性分析

通过试验研究胶粉改性沥青、SBS改性沥青及混合改性沥青微观组织结构、高温环境与低温环境对其流变性能影响。测试结果表明:胶粉改性沥青、SBS改性剂与沥青相容性较好,但橡胶粉改性沥青与石材之间界面附着力高于SBS改性沥青。DSR试验表明:橡胶粉改性沥青温度具备低温耐裂性及高温耐变形性。综上对混合改性沥青流变性能研究,旨在为我国研发新型高性能沥青提供有效技术支持。

预处理胶粉改性沥青性能影响研究

为研究适用于抽水蓄能电站工程的黏度高、耐老化、温度敏感性低的沥青,采用糠醛抽出油浸润及微波辐射预处理胶粉的方法,制备胶粉改性沥青,并开展室内沥青性能试验,分析糠醛抽出油掺量及微波功率对沥青性能的影响。试验结果表明:随糠醛抽出油掺量增加,沥青针入度和延度提高,软化点和黏度降低,糠醛抽出油掺量为3%时,沥青离析软化点差最小。随微波功率增大,沥青黏度、离析软化点差和劲度模量先减小后增大。综上,在糠醛抽出油掺量为3%,微波功率为1000 W时,胶粉改性沥青的工作性和低温抗裂性能最优。

改性剂对废橡胶粉复合改性沥青性能影响的研究进展

废橡胶粉改性沥青(CRMA)技术能较好地改善沥青路面的高低温性能,为进一步提升路用性能和解决储存稳定性问题,通常在基质沥青中同时加入其他改性剂进行复合改性。本文介绍了近年来国内外应用较多的苯乙烯-丁二烯-苯乙烯嵌段共聚物(SBS)、多聚磷酸(PPA)和石墨烯等改性剂与废橡胶粉对沥青进行复合改性的研究成果,分析总结了复合改性沥青的优越性和存在的不足,为更深入的复合改性沥青技术研究提供一定的指导作用。

胶粉复合改性沥青-钢渣沥青混合料室内压实性能分析

通过室内马歇尔击实试验分析胶粉复合改性沥青-钢渣沥青混合料压实性能的影响因素,重点分析不同合成级配、击实温度、细料用量、填料用量、油石比以及添加温拌剂等对其体积性能和力学性能的影响。试验结果表明钢渣沥青混合料室内可压实性对矿料合成级配敏感,压实温度不宜低于165℃以避免压实度不足。冬季低温施工可掺入温拌剂补偿近20℃温度损失的影响。配合比在正常波动范围内可显著影响其压实性能,提出影响空隙率变化的多因素关系式可用于指导现场施工配合比控制。空隙率和劈裂强度呈负线性相关性,现场空隙率宜按低值控制以保证长期使用耐久性。